1. Field of the Invention
The present invention relates, in general, to double chamber single directional spiral tuyeres for blast furnaces and, more particularly, to a double chamber single directional spiral tuyere for blast furnaces, which supplies a hot blast having a temperature of about 1200° C. into a blast furnace and has an improved cooling structure capable of increasing the cooling performance of the tuyere, thereby having an increased expected lifespan.
2. Description of the Related Art
Generally, blast furnaces used in iron mills are furnaces for manufacturing pig iron. In a conventional blast furnace, iron ore, such as agglomerated ore or sized ore, which is the raw material, is processed through smelting reduction using reduction gas, thus producing pig iron. During the iron manufacture, the reduction gas is generated by burning coke, which is the fuel, using a hot blast having a temperature of about 1200° C. supplied into the furnace through a tuyere.
In the prior art, a variety of tuyeres has been used for supplying a hot blast into blast furnaces. Among the variety of conventional tuyeres for blast furnaces, a double chamber spiral tuyere having a high cooling capacity has been preferably used. As shown in FIGS. 1 and 2, a conventional double chamber spiral tuyere for blast furnaces comprises a body unit 10, a spiral unit 20 and a cover unit 30. As desired, a hard facing 40 may be further provided on the double chamber spiral tuyere to minimize abrasion and breakage caused by collisions between the fuel and raw material, which drop downwards after being put into the top of the blast furnace.
The above-mentioned conventional double chamber spiral tuyere for blast furnaces has double chamber-type cooling passages. In the field, the technical term “double chamber” means that the tuyere has two chambers, so that, if cooling water leaks in the first chamber due to damage, the cooling water supply for the first chamber is stopped, and the second chamber continues its function, thus allowing the tuyere to temporarily continue its service until replaced.
As shown in FIGS. 2(a) and 2(b), the conventional double chamber spiral tuyere for blast furnaces comprises two chambers. Described in detail, a first spiral passage 21, a second spiral passage 22, a third spiral passage 23 and a fourth spiral passage 24 defined in the spiral unit 20 form one chamber, which is called a “nose chamber”, while a body main passage 11 and a body nose passage 12 defined in the body unit 10 form another chamber, which is called a “body chamber”.
In the related art, the above-mentioned double chamber spiral tuyere for blast furnaces has been preferably used in most blast furnaces, and supplies a hot blast under high pressure into a blast furnace through a hot blast outlet nozzle 50, thus causing coke to be burnt by the hot blast in the furnace. To allow the tuyere to resist a high temperature operational atmosphere condition, cooling water is supplied to the body chamber and the nose chamber, thus cooling the tuyere to minimize thermal degradation or thermal damage to the tuyere.
In other words, the double chamber spiral tuyere for blast furnaces is advantageous in that, even if the nose chamber of the tuyere is damaged due to burn or wear, the tuyere can continue its function while the nose chamber, having been damaged is closed and only the body chamber executes its cooling function until a scheduled period before regularly scheduled maintenance has expired.
However, the conventional double chamber spiral tuyere for blast furnaces is problematic in that the flowing direction of cooling water has to reverse at an angle of 180° at the junction between the first spiral passage 21 and the second spiral passage 22 of the nose chamber, as shown in FIGS. 2(a) and 2(b), thus causing unnecessary pressure loss.
Described in detail, when viewing the hot blast outlet nozzle 50 of the tuyere from the right to the left in the drawings, cooling water flows counterclockwise in the first spiral passage 21 and the third spiral passage 23, thus being supplied to the nose chamber, while cooling water flows clockwise in the second spiral passage 22 and the fourth spiral passage 24, thus being discharged from the nose chamber. Because cooling water circulates in opposite directions in the nose chamber as described above, the flowing direction of the cooling water must reverse at an angle of 180° at a reverse-turning part 25. This is caused by the structural limitation of the cooling passages, in which cooling water having been supplied into the tuyere through a nose inlet 3 does not flow to the first spiral passage 21, but primarily flows to the third spiral passage 23. Due to the spatial limitation of the cooling passages, if such a reverse-turning part 25 is not provided in the cooling passages, the cooling water cannot be circulated to a nose outlet 4 of the tuyere.
Thus, body cooling water, which has been supplied into the body chamber through a body inlet 1, circulates in the body chamber of the tuyere along a passage, as shown by the arrows E in FIG. 2(b), prior to being discharged from the tuyere through a body outlet 2. Nose cooling water, which has been supplied into the nose chamber through the nose inlet 3, circulates in the nose chamber of the tuyere along the above-mentioned spiral passages in the sequence {circle around (a)}→{circle around (b)}→{circle around (c)}→{circle around (d)}→{circle around (e)}→{circle around (f)}→{circle around (g)}→{circle around (h)}, in which the cooling water reverses its flowing direction at positions {circle around (d)} and {circle around (e)} and, thereafter, continues circulating prior to being discharged from the tuyere through the nose outlet 4.
Further, the second problematic issue of the conventional double chamber spiral tuyere is, when cooling water flows through the junction at which the spiral unit 20 is in contact with the cover unit 30, cooling water having been supplied into the tuyere cannot flow through a normal passage in the order of the third spiral passage 23→the first spiral passage 21→the second spiral passage 22→the fourth spiral passage 24, but is shunted such that the cooling water directly flows from the third spiral passage 23 to the fourth spiral passage 24. In the above state, the cooling water is discharged without reaching the nose of the tuyere, thus causing loss of flow in the nose chamber and reducing the cooling performance of the tuyere, and reducing the expected lifespan of the tuyere.